I'll add what's unique about my design. It's a tight .335" neck (turning required), 40 degree shoulder, about .007" per inch body taper and the neck has been increased to .405" in length. It's better than any other design, "for me", because it has all the features I wanted it to have, each for a certain reason.
Body taper... Fine for easy extraction but, adds about maximum increase in capacity blowing the body out can provide.
40 degree... Less throat errosion, better physical protection for the throat, in theory.
Extra long neck length... Reduces throat errosion to almost nothing on the bigest 30's, I'm told.
.335" NK... Better case life and consistancy.
The case itself was chosen for a fast 30 cal because of the extra well designed, stronger 338 Lapua parent case and the quality and consistancy it has an undisputed reputation for. The fatter case may have better efficiency in the end as well, getting better velocity with the same pressure. Case life and consitancy, good throat life at maximum speed with top pressures if it groups well there was what led me.
I just checked the water capacity on the two cases I fire formed the other day, they were 116.1gr and 116.3gr to the top, no bubble. Should be a grain or three over the 300 Ultra is all but, that with the possibility it may yield better MV at the same pressure gives me the opportunity to opperate at lower pressre and the same speed for even better case life over the Ultra, or achieve more speed at the same pressure... we shall see soon.
I loaded the Ultra I have and the 30/388 40 deg Imp both up with 200gr Accubonds using 90gr Retumbo and checked the MV, the Ultra with a 26" tube and the 30/338 LI with its 30". The Ultra was 3045 fps ave, and the LI was at 3080 fps. The longer bbl accounts for the difference in my judgement but, the LI showed less pressure on the primer by far... it was very noticable.
One final thing, I almost forgot was, I had the OAL up to 3.835" on the Ultra, which was .015" into the lands and MV was 3080 fps on it, coming back to 3.660" OAL reduced the MV to 3045 fps... For comparison sake, the LI's OAL was right in the middle of those two there, at 3.750" and right on the lands. The case on the LI is shorter so the effective case capacity may be closer to equal if the Ultra is compared to the LI when seated out to 3.835" and not 3.660", I'm not sure if the bullet's eating up about the same capacity at which OAL tho, something to look into...
One other thing to consider if the longer OAL is a better "apples to apples" comparison if you're focusing on the two's initial water capacity as a potential performance indicator is this, you may be single feeding the Ultra "only" to get those better MV's, where as the LI will easily allow you to use a standard 700 action and longer box, which can be fitted with minor work... More things to consider is all. [img]images/icons/wink.gif[/img]